A number of significant enhancements to the ciss driver:

1.  The FreeBSD driver was setting an interrupt coalesce delay of 1000us
for reasons that I can only speculate on.  This was hurting everything
from lame sequential I/O "benchmarks" to legitimate filesystem metadata
operations that relied on serialized barrier writes.  One of my
filesystem tests went from 35s to complete down to 6s.

2.  Implemented the Performant transport method.  Without the fix in
(1), I saw almost no difference.  With it, my filesystem tests showed
another 5-10% improvement in speed.  It was hard to measure CPU
utilization in any meaningful way, so it's not clear if there was a
benefit there, though there should have been since the interrupt handler
was reduced from 2 or more PCI reads down to 1.

3.  Implemented MSI-X.  Without any docs on this, I was just taking a
guess, and it appears to only work with the Performant method.  This
could be a programming or understanding mistake on my part.  While this
by itself made almost no difference to performance since the Performant
method already eliminated most of the synchronous reads over the PCI
bus, it did allow the CISS hardware to stop sharing its interrupt with
the USB hardware, which in turn allowed the driver to become decoupled
from the Giant-locked USB driver stack.  This increased performance by
almost 20%.  The MSI-X setup was done with 4 vectors allocated, but only
1 vector used since the performant method was told to only use 1 of 4
queues.  Fiddling with this might make it work with the simpleq method,
not sure.  I did not implement MSI since I have no MSI-specific hardware
in my test lab.

4.  Improved the locking in the driver, trimmed some data structures.
This didn't improve test times in any measurable way, but it does look
like it gave a minor improvement to CPU usage when many
processes/threads were doing I/O in parallel.  Again, this was hard to
accurately test.

1 files changed, 51 insertions, 57 deletions

diff --git a/sys/dev/ciss/cissvar.h b/sys/dev/ciss/cissvar.h
index 05e64fa..a3df3c2d 100644
--- a/sys/dev/ciss/cissvar.h
+++ b/sys/dev/ciss/cissvar.h
@@ -30,6 +30,8 @@
  * CISS adapter driver datastructures
  */
 
+typedef STAILQ_HEAD(, ciss_request)	cr_qhead_t;
+
 /************************************************************************
  * Tunable parameters
  */
@@ -61,7 +63,7 @@
  *
  * If the delay is set to 0, interrupts are delivered immediately.
  */
-#define CISS_INTERRUPT_COALESCE_DELAY	1000
+#define CISS_INTERRUPT_COALESCE_DELAY	0
 #define CISS_INTERRUPT_COALESCE_COUNT	16
 
 /*
@@ -80,22 +82,6 @@ typedef struct proc	d_thread_t;
 #endif
 
 /************************************************************************
- * Command queue statistics
- */
-
-#define CISSQ_FREE	0
-#define CISSQ_BUSY	1
-#define CISSQ_COMPLETE	2
-#define CISSQ_NOTIFY	3
-#define CISSQ_COUNT	4
-
-struct ciss_qstat
-{
-    u_int32_t	q_length;
-    u_int32_t	q_max;
-};
-
-/************************************************************************
  * Driver version.  Only really significant to the ACU interface.
  */
 #define CISS_DRIVER_VERSION	20011201
@@ -110,7 +96,7 @@ struct ciss_qstat
  */
 struct ciss_request
 {
-    TAILQ_ENTRY(ciss_request)	cr_link;
+    STAILQ_ENTRY(ciss_request)	cr_link;
     int				cr_onq;		/* which queue we are on */
 
     struct ciss_softc		*cr_sc;		/* controller softc */
@@ -124,9 +110,19 @@ struct ciss_request
 #define CISS_REQ_POLL		(1<<2)		/* submitter polling */
 #define CISS_REQ_DATAOUT	(1<<3)		/* data host->adapter */
 #define CISS_REQ_DATAIN		(1<<4)		/* data adapter->host */
+#define CISS_REQ_BUSY		(1<<5)		/* controller has req */
 
     void			(* cr_complete)(struct ciss_request *);
     void			*cr_private;
+    int				cr_sg_tag;
+#define CISS_SG_MAX		((CISS_SG_FETCH_MAX << 1) | 0x1)
+#define CISS_SG_1		((CISS_SG_FETCH_1 << 1) | 0x01)
+#define CISS_SG_2		((CISS_SG_FETCH_2 << 1) | 0x01)
+#define CISS_SG_4		((CISS_SG_FETCH_4 << 1) | 0x01)
+#define CISS_SG_8		((CISS_SG_FETCH_8 << 1) | 0x01)
+#define CISS_SG_16		((CISS_SG_FETCH_16 << 1) | 0x01)
+#define CISS_SG_32		((CISS_SG_FETCH_32 << 1) | 0x01)
+#define CISS_SG_NONE		((CISS_SG_FETCH_NONE << 1) | 0x01)
 };
 
 /*
@@ -199,12 +195,14 @@ struct ciss_softc
     struct resource		*ciss_cfg_resource;	/* config struct interface window */
     int				ciss_cfg_rid;		/* resource ID */
     struct ciss_config_table	*ciss_cfg;		/* config table in adapter memory */
+    struct ciss_perf_config	*ciss_perf;		/* config table for the performant */
     struct ciss_bmic_id_table	*ciss_id;		/* ID table in host memory */
     u_int32_t			ciss_heartbeat;		/* last heartbeat value */
     int				ciss_heart_attack;	/* number of times we have seen this value */
 
+    int				ciss_msi;
     struct resource		*ciss_irq_resource;	/* interrupt */
-    int				ciss_irq_rid;		/* resource ID */
+    int				ciss_irq_rid[CISS_MSI_COUNT];		/* resource ID */
     void			*ciss_intr;		/* interrupt handle */
 
     bus_dma_tag_t		ciss_parent_dmat;	/* parent DMA tag */
@@ -212,16 +210,21 @@ struct ciss_softc
 
     u_int32_t			ciss_interrupt_mask;	/* controller interrupt mask bits */
 
+    uint64_t			*ciss_reply;
+    int				ciss_cycle;
+    int				ciss_rqidx;
+    bus_dma_tag_t		ciss_reply_dmat;
+    bus_dmamap_t		ciss_reply_map;
+    uint32_t			ciss_reply_phys;
+
     int				ciss_max_requests;
     struct ciss_request		ciss_request[CISS_MAX_REQUESTS];	/* requests */
     void			*ciss_command;		/* command structures */
     bus_dma_tag_t		ciss_command_dmat;	/* command DMA tag */
     bus_dmamap_t		ciss_command_map;	/* command DMA map */
     u_int32_t			ciss_command_phys;	/* command array base address */
-    TAILQ_HEAD(,ciss_request)	ciss_free;		/* requests available for reuse */
-    TAILQ_HEAD(,ciss_request)	ciss_busy;		/* requests in the adapter */
-    TAILQ_HEAD(,ciss_request)	ciss_complete;		/* requests which have been returned by the adapter */
-    TAILQ_HEAD(,ciss_request)	ciss_notify;		/* requests which are defered for processing */
+    cr_qhead_t			ciss_free;		/* requests available for reuse */
+    cr_qhead_t			ciss_notify;		/* requests which are defered for processing */
     struct proc			*ciss_notify_thread;
 
     struct callout		ciss_periodic;		/* periodic event handling */
@@ -329,71 +332,59 @@ struct ciss_softc
 static __inline void							\
 ciss_initq_ ## name (struct ciss_softc *sc)				\
 {									\
-    TAILQ_INIT(&sc->ciss_ ## name);					\
+    STAILQ_INIT(&sc->ciss_ ## name);					\
     CISSQ_INIT(sc, index);						\
 }									\
 static __inline void							\
 ciss_enqueue_ ## name (struct ciss_request *cr)				\
 {									\
-    int		s;							\
 									\
-    s = splcam();							\
-    TAILQ_INSERT_TAIL(&cr->cr_sc->ciss_ ## name, cr, cr_link);		\
+    STAILQ_INSERT_TAIL(&cr->cr_sc->ciss_ ## name, cr, cr_link);		\
     CISSQ_ADD(cr->cr_sc, index);					\
     cr->cr_onq = index;							\
-    splx(s);								\
 }									\
 static __inline void							\
 ciss_requeue_ ## name (struct ciss_request *cr)				\
 {									\
-    int		s;							\
 									\
-    s = splcam();							\
-    TAILQ_INSERT_HEAD(&cr->cr_sc->ciss_ ## name, cr, cr_link);		\
+    STAILQ_INSERT_HEAD(&cr->cr_sc->ciss_ ## name, cr, cr_link);		\
     CISSQ_ADD(cr->cr_sc, index);					\
     cr->cr_onq = index;							\
-    splx(s);								\
 }									\
 static __inline struct ciss_request *					\
 ciss_dequeue_ ## name (struct ciss_softc *sc)				\
 {									\
     struct ciss_request	*cr;						\
-    int			s;						\
 									\
-    s = splcam();							\
-    if ((cr = TAILQ_FIRST(&sc->ciss_ ## name)) != NULL) {		\
-	TAILQ_REMOVE(&sc->ciss_ ## name, cr, cr_link);			\
+    if ((cr = STAILQ_FIRST(&sc->ciss_ ## name)) != NULL) {		\
+	STAILQ_REMOVE_HEAD(&sc->ciss_ ## name, cr_link);		\
 	CISSQ_REMOVE(sc, index);					\
 	cr->cr_onq = -1;						\
     }									\
-    splx(s);								\
     return(cr);								\
 }									\
-static __inline int							\
-ciss_remove_ ## name (struct ciss_request *cr)				\
-{									\
-    int			s, error;					\
-									\
-    s = splcam();							\
-    if (cr->cr_onq != index) {						\
-	printf("request on queue %d (expected %d)\n", cr->cr_onq, index);\
-	error = 1;							\
-    } else {								\
-	TAILQ_REMOVE(&cr->cr_sc->ciss_ ## name, cr, cr_link);		\
-	CISSQ_REMOVE(cr->cr_sc, index);					\
-	cr->cr_onq = -1;						\
-	error = 0;							\
-    }									\
-    splx(s);								\
-    return(error);							\
-}									\
 struct hack
 
 CISSQ_REQUEST_QUEUE(free, CISSQ_FREE);
-CISSQ_REQUEST_QUEUE(busy, CISSQ_BUSY);
-CISSQ_REQUEST_QUEUE(complete, CISSQ_COMPLETE);
 CISSQ_REQUEST_QUEUE(notify, CISSQ_NOTIFY);
 
+static __inline void
+ciss_enqueue_complete(struct ciss_request *ac, cr_qhead_t *head)
+{
+
+    STAILQ_INSERT_TAIL(head, ac, cr_link);
+}
+
+static __inline struct ciss_request *
+ciss_dequeue_complete(struct ciss_softc *sc, cr_qhead_t *head)
+{
+    struct ciss_request  *ac;
+
+    if ((ac = STAILQ_FIRST(head)) != NULL)
+        STAILQ_REMOVE_HEAD(head, cr_link);
+    return(ac);
+}
+
 /********************************************************************************
  * space-fill a character string
  */
@@ -408,3 +399,6 @@ padstr(char *targ, const char *src, int len)
 	}
     }
 }
+
+#define ciss_report_request(a, b, c)	\
+	_ciss_report_request(a, b, c, __FUNCTION__)